Developmental regulation of cloned superabundant embryo mRNAs in soybean☆

[摘要] WehaveinvestigatedthedevelopmentalexpressionandreiterationfrequencyofgenesencodingfoursoybeanembryomRNAs.AcDNAlibraryofmid-maturation-stagemRNAsequenceswasconstructedbycloningintopBR322.PlasmidsrepresentingdistinctsuperabundantmRNAspecies(>10,000moleculespercell)wereselectedfromthelibrary,andfourcloneswerechosenforfurtherinvestigation.HybridizationexperimentswithmRNAblotsshowedthatthreeofthecloneshybridizedtoasinglemRNA,eachofwhichhadauniquesize.Oneclone,however,wascomplementarytotwomRNAshavingdistinctmolecularweights.TheprevalenceofeachmRNAwasquantitatedatdistinctdevelopmentalperiods.TheresultsshowedthatthemRNAsaccumulatedduringearlyembryogenyandthendecayedpriortoseeddehydration.Inaddition,theclonedtranscriptswereeitherundetectable,orpresentatverylowlevels(<1moleculeper20cells)inleafcells,suggestingthattheirstructuralgenesareregulatedprimarilyatthetranscriptionallevel.ThereiterationfrequencyofgenesencodingallfourmRNAswasmeasuredbyhybridizinglabeled,single-strandedplasmidDNAprobeswithanexcessofembryoand/orleafDNAs.Thefindingsdemonstratedthateachmessageisencodedbyasmallmultigenefamilycontaining⪕5members.NodetectabledifferencesinhybridizationrateswereobservedwithleafandembryoDNAs,indicatinganabsenceofselectivegeneamplificationduringembryogenesis.

[学科分类] 生物科学（综合）